Photoluminescence properties of Yb²⁺ ions doped in the perovskites CsCaX₃ and CsSrX₃ (X = Cl, Br, and I) – a comparative study

Abstract

The Yb(2+)-doped perovskite derivatives CsMX3 (M = Ca and Sr; X = Cl, Br, and I) are ideal systems for obtaining a detailed insight into the structure-luminescence relationship of divalent lanthanides. The investigation of the respective photoluminescence properties yielded two emission bands in the violet and blue spectral range for all compounds, which are assigned to the spin-allowed and spin-forbidden 5d-4f transitions, respectively. The impact on their energetic positions is dependent on both the covalency of the Yb(2+)-halide bond and the corresponding bond length in agreement with expectations. The excitation spectra provide a detailed fine structure at low temperatures and can be partly interpreted separating the 4f(13) core from the 5d electron in the excited state. The local crystal field in CsSrI3:Yb(2+) provides a special case due to the trigonal distortion induced by the crystal structure that is clearly evident in the luminescence features of Yb(2+). The structure-property relationship of several spectroscopic key quantities of Yb(2+) in this series of halides is analyzed in detail and parallels the properties of Eu(2+) ions doped in the given perovskites.

Fully‐Inorganic Trihalide Perovskite Nanocrystals: A New Research Frontier of Optoelectronic Materials

“…[194,195] Additionally, there exist contradictory results on the energy transfer in CsPbX 3 nano-phosphors. [33,197] In summary, we are convinced that the fascinating achievements to date will encourage more researchers to make additional efforts to tackle these challenges in the future. More investigations are also needed to reveal the correlations between structure (especially the surface states) and optoelectronic properties.…”

Progress on lead-free metal halide perovskites for photovoltaic applications: a review

“…Alkaline-earth metal halide perovskites with a basic formula ABX 3 (B = Mg, Ca, Sr; X = Cl, Br, I) employing inorganic A-site cations (e.g. K + , Cs + ) have been studied extensively with regard to their photoluminescence properties resulting from doping with rare earth metal cations such as Eu 2+ , Yb 2+ , or Tm 2+ [119–123]. Until now, only a few research studies have been focused on alkaline-earth-metal-based halide perovskites for photovoltaic applications, which is due to the high calculated band gaps and extreme sensitivity towards humidity [118].…”

“…In particular, alkaline-earth metal halide perovskites of the family CsBX 3 (B = Mg, Ca, Sr; X = Cl, Br, I) have been investigated with regard to their optical properties (e.g. photoluminescence) due to doping with rare earth metal ions such as Eu 2+ [119–121], Tm 2+ [122], and Yb 2+ [123]. In case of CsBI 3 :Eu 2+ and CsBBr 3 :Eu 2+ (B = Mg, Ca, Sr), divalent Eu 2+ metal cations occupy the sixfold, octahedrally coordinated alkaline-earth metal sites of the host compound [120, 121].…”

“…In case of CsBI 3 :Eu 2+ and CsBBr 3 :Eu 2+ (B = Mg, Ca, Sr), divalent Eu 2+ metal cations occupy the sixfold, octahedrally coordinated alkaline-earth metal sites of the host compound [120, 121]. For thulium- and ytterbium-doped perovskites, the situation is quite similar [122, 123]. The applicability of these luminescent materials, for example in optoelectronic devices, is, however, limited because of the sensitivity towards moisture [121].…”

Characterizations of CsSrCl3:Ce Crystalline Scintillator

“…Auger-free luminescence (AFL), that is, radiative electric transition from the valence band to the outermost core band, in undoped CsMgCl 3 , CsCaCl 3 , and CsSrCl 3 crystals have been intensely studied because of their interesting characteristics such as fast decay times with high thermal stability. (6)(7)(8)(9) The rare-earth-, transition-metal-, and s 2 -ion-doped perovskite chloride crystals have attracted the most attention as the phosphor, (10)(11)(12)(13)(14)(15) magnetic material, (16)(17)(18)(19) and scintillator, (19)(20)(21)(22)(23) and then their crystal growth and characterizations have been reported by some researchers. Among the rare-earth-doped crystals, CsCaCl 3 :Eu and CsSrCl 3 :Eu are proposed to be promising X-ray and gamma-ray scintillators because of their high light yield (~18000 photons/MeV) owing to a 5d-4f allowed transition of Eu…”